Difference between revisions of "Load and solar resource comparison"
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*Design daily watt-hours required | *Design daily watt-hours required | ||
| − | + | ====Step 1: Determine monthly ratio of consumption to solar resource==== | |
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*'''Month:''' The month of the year. | *'''Month:''' The month of the year. | ||
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*'''Ratio =''' Average daily watt-hours required ÷ Average monthly insolation | *'''Ratio =''' Average daily watt-hours required ÷ Average monthly insolation | ||
| − | == | + | ====Step 2: Determine design values==== |
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Revision as of 10:00, 19 December 2020
The design process for an off-grid PV system should use conservative, worst-case values to ensure that the system is capable of meeting the energy needs of users throughout the year. There are many locations that have a significant seasonal variance in solar resource due to poor weather or latitude. Many off-grid PV systems will see a significant variance in how loads are used throughout the year, especially in locations that are only seasonally occupied. These two different factors - load usage vs. solar resource - make it important to determine what month to use in the system design as the worst-case scenario. An analysis of loads and usage could be performed on a monthly basis, but the most drastic shift in usage likely occurs between the major seasons in a given region meaning two to four times per year. Determining the worst-case month can be done using a simple table and a quick calculation. The values and calculation can be performed in Wh or kWh - the ratio is what is important. The two following values used for the design should be chosen from the month with the highest ratio of average daily watt-hours relative to average monthly insolation:
- Design daily insolation
- Design daily watt-hours required
Step 1: Determine monthly ratio of consumption to solar resource
| Month | Average daily insolation | Average daily watt-hours required | Ratio | |||||
|---|---|---|---|---|---|---|---|---|
| January | ||||||||
| February | ||||||||
| March | ||||||||
| April | May | |||||||
| June | ||||||||
| July | ||||||||
| August | ||||||||
| September | ||||||||
| October | ||||||||
| November | ||||||||
| December |
- Month: The month of the year.
- Average daily insolation: Solar resource data obtained for the location from Weather and solar resource data sources.
- Average daily watt-hours required from load evaluation.
- Ratio = Average daily watt-hours required ÷ Average monthly insolation
Step 2: Determine design values
| Design daily insolation | = Average monthly insolation from month with the highest ratio ÷ 30 |
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| Design daily watt-hours required | = Average daily watt-hours from month with the highest ratio |
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